Apparatus for measuring electric capacity.



PATENTED APR. 9, 1907.

' 1T0c 850,064. v

HVSHOEMAKER. I APPARATUS FOR MEASURING ELECTRIC CAPACITY.

APPLIOA'QION FILED 00159, 1906.

L .HBATTPRNEY UNITED STATES PATENT OFFICE.

HARRY sHoitMAKER, or JERSEY CITY, NEW JERSEY APPARATUS EOR MEASURING ELECTRIC CAPACITY.

1'0 all whom, it may concern:

Be it known that I, HARRY SHOEMAKER, a citizen of the United States, residing at Jersey City, in the county of Hudson and State of New Jersey, havefinvented-ainew and useful Apparatus for Measuring "Electric Ca pacity, of which the following is' a specification.

My invention relates to the measurement or determination of the electric capacity of a condenser or a condenser-like device.

erably non-inductive, is connected in one arm of thebridge along with the condenser K, whose capacity is variable and known To the other arm of the bridge are connected the variable-resistance R, preferably noninductive, and the condenser or like device C whose electrostatic capacity is to be determined; A magneto or other tele hone receiver T is connected the bridge. The common terminal of the resistances R and R is connected with the reed or vibrator V, which carries at or near its extremity a contact-piece a, adapted to alternately engage the stationary contacts I) and c. A battery or other source of current B is connected between the common terminal of the condensers K and C and the contact a, and the contact b is connected directly to the common terminal of the condensers K and C. An

electromagnet M has its winding included serially in circuit with a battery B, the switch S, the contact f on the adjustable screw g passing through a frame or member h. The contact e is preferably insulated from the vibrator V. When the switch' S is closed, the

' vibrator or reed V is 'setin motion by the electromagnet M, and when attracted the magnet-circuit is broken, and the vibrator V then springs back against contact f, again closing the magnetcircuit. -This operation.

is repeated at ,a relatively rapid rate so long 5 as the switch S is closed.

7 With the parts in position shown, the bat- Specification of Letters Patent.

, Application filed October 9,1906. Serial No. 338.100.

PatentedApril 9,1907.

tery B has charged the condensers K and C through the resistances It and R", respectively. The contact a is carried against contact 6, however, by the return of the vibrator V, with resultant discharge of the condensers K and C through the respective resistances R and R. The riders r and r (or the plugs) if resistance-boxes are used are suitably adjusted, as is also the variable condenser K. Adjustments are made of the resistances and of the condenser K until no noise or tone is heard in the telephone T. When this condition is obtained, an electrical balance has been struck, and by noting the capacity of K, which is always known, and the values oi the resistances R and R, which are in circuit, the capacity of C is immediatelydetermined.

Since the telephone is an extremely sensitive instrument and is responsive to the slightest current; a condition of delicate balance is assured when no sound occurs in the telephone.

By the apparatus above described measurements or determinations are quickly and most accurately made. The rate of charge and discharge of the condensers K and C may be varied by changing the period of the vibrator V, which may be done either by changing the adjustment of the screw 9 or by changing the natural period of the vibrator V in well-known ways.

The above-described apparatus may take the form of a measuring instrument by inclosing the resistances R R, the variable condenser K, the batteries B B, and the vibrator apparatus in -a suitable box or receptacle, the various contacts and adjustable parts being arranged on hard-rubber slabs secured within the box.

What I claim is 1. In combination, a Wheatstone bridge,

a known capacity connected in one arm there-- of, an unknown capacity connected in the other arm thereof, and means for automatically charging and discharging said capacities.

2. In combination, a VVheatstone bridge, a known capacity and resistance connected in one arm thereof, a known resistance and an unknown capacity connected in another arm thereof, means for automatically charging and discharging said capacities, and an instrument for indlcating when said bridge f has been balanced.

3.- In combination, a Wheatstpne bridge, a known capacity connected in one arm thereof, an unknown capacity connected in IIO another arm thereof, a vibrator and a source of energy, said bridge as a whole connected in series with said vibrator and source of energy, and means for discharging said capacities after each charge controlled by said vibrator.

4. In combination, aI/Vheatstone bridge, an automatic vibrator and source of energy serially connected with each other and with said bridge as a whole, a known capacity connected in one arm of the bridge, an unknown capacity connected inanother arm of the bridge, and an instrument for indicating when the bridge has beenbalanced.

5. In combination, a I/Vheatstone bridge, a known capacity connected .in one arm thereof, an unknown capacity connected in another arm thereof, and means for alternately and rapidly charging and discharging said bridge 6 The combination with a Wheatstone bridge, a device to be tested included in an arm of said bridge, of an external source of energy, an indicating instrument and automatic means for rapidly and alternately charging and discharging-said bridge.

7. In combination, known and unknown capacities and resistances, means for automatically charging and discharging said capacities, and an indicating instrument.

8. In combination, a Wheatstone bridge, resistances and known and unknown capacities in the arms thereof, an indicating instrument, a circuit including said bridge as a whole and a'souree of energy, and automatic 'means for alternately closing said circuit through said source of energy and a short circuit. 1

9. In combination, a VVheatstone bridge, known and unknown capacities connected in the arms thereof, an indicating instrument,

a circuit including said bridge as a whole and.

containing respectively known and unknown capacities, an indicating instrument, a circult containing a source of energy and said branched circuits, and means for alternately connecting said branched circuits through said source of energy and short-circuiting said branched circuits.

11. In combination, branched circuits, an indicating instrument, electrical devices of similar characteristics connected respectively in said branched circuits, one of said devices having a known quantity of electrical action, the other an unknown quantity of electrical action, a circuit including said branched circuits and a source of energy, and means for alternately closing the circuit through said source of energy and through a short-circuit.

12. In combination, a Wheatstone bridge, known and unknown capacities vconnected in the arms thereof, an indicating instrument, a circuit'including a source ofenergy and said bridge as a whole, and an automatic vibrator alternately closing said circuit through said source of energy and short-circuiting said bridge as a whole.

In witness whereof I have hereunto affixed my signature in the presence of the two subscribing witnesses.

HARRY SIIOEMAKER. Witnesses JOHN FIRTH, G. M. BUCHANAN. 

